1. Technical Field
Embodiments of the present disclosure relate to measuring apparatus and, more particularly, to a focus apparatus of an image measuring system.
2. Description of Related Art
Auto-focus systems are used in optical measuring instruments, such as image measuring systems. Usually, the image measuring systems use a charge coupled device (CCD) camera to capture an image of a surface of an object, and focus a lens based on the contrast of the image. However, since the image is first captured by a CCD camera, it is difficult to precisely focus on a low contrast surface, such as a reflective surface using the contrast method mentioned above.
What is needed, therefore, is an improving focus apparatus of an image measuring system.